#include <iostream>
#include <string>

using namespace std;

const int N = 1e5 + 10;

int n;
char str[N];
char res[N];

int main()
{
    cin >> n;
    cin >> str;

    int cnt[26] = { 0 };

    int maxCount = 0, maxIndex = 0;
    for (int i = 0; i < n; i++)
    {
        cnt[str[i] - 'a']++;

        if (cnt[str[i] - 'a'] > maxCount) {
            maxCount = cnt[str[i] - 'a'];
            maxIndex = str[i] - 'a';
        }
    }

    if (maxCount > (n + 1) / 2) {
        cout << "no" << endl;
    }
    else {
        cout << "yes" << endl;

        int i = 0;
        while (maxCount--) {
            res[i] = maxIndex + 'a';
            i += 2;
        }

        for (int j = 0; j < 26; j++) {

            if (cnt[j] > 0 && j != maxIndex) {

                while (cnt[j]--) {

                    if (i >= n)
                        i = 1;

                    res[i] = j + 'a';

                    i += 2;
                }
            }

        }
        for (int i = 0; i < n; i++)
            cout << res[i];
    }
    return 0;
}